The invention refers to a transmitter/antenna plug-in board for selective connection of coaxial lines.
It is known to link coaxial lines through a transmission line connection which is manually pluggable on flange sockets of the coaxial lines with the flange sockets incorporated in a front panel. The transmission line connection which assigns a certain transmitter to a certain antenna (or vice versa) includes an outer conductor and an inner conductor and is provided with a device acting on the carrier safety loop.
Such plug-in board are installed primarily to provide a back up or emergency service. Therefore,the positioning of the pluggable transmission line connection is rarely changed. Still, such plug-in boards should be designed with low reflection and should be secured against unintentional switching. In addition, a desired or required change should be possible in a fast manner without endangering the operator.
In general, these requirements are met by designing the pluggable transmission line connection as bow-type plug with U-shaped transmission line and with licks which are in kinematic connection with microswitches or rotary switches arranged behind the front panel of the plug-in board. The carrier safety loop is guided via the contacts of these microswitches or rotary switches with the contact being open when the locking mechanism of the bow-type plug is released.
The known plug-in boards with their bow-type plugs are thus composed of numerous and complicated parts which must be additionally mounted at narrow tolerances. Moreover, the use of switches for the carrier safety loop does not attain an absolute safety mechanism as the switches contain springs which may break and thus inadvertently keep the carrier safety loop in a closed state.